Vokul Tactical Red Dot Sight 20mm Picatinny Weaver Rail Mount for Pistol Gun The item adjustment for windage and elevation illuminated cross-hairs for day & night shooting. Shipping from USA, 3-5 Working Day Arrived Cross-hair being used instead of the traditional front sight and notch base the aiming speed, accuracy and percentage of hits are greatly increased Its outer covering is made of high - strength aluminium alloy and undergoes special anti-corrosive treatment, and the surface of all the optical spare parts are plated with anti-reflection coating It is anti vibration, fog-proof and shock-resistant Tube diameter: 1 inch